Process gases containing acid gases are generated in many industrial processes. Such an industrial process may be the combustion of a fuel such as coal, oil, peat, waste, or similar combustible, in a combustion plant such as a power plant, whereby a hot process gas or “flue gas” is generated containing pollutants including acid gases. The generated process gas requires treatment for removal of at least a portion of the acid gases present therein prior to release of the process gas into the atmosphere. Such process gas treatment may be provided in a wet scrubber such as that disclosed in EP 0 162 536. The disclosed wet scrubber comprises an absorption liquid, which is brought into contact with the process gas for absorption of at least a portion of the acid gases from the process gas. The absorption liquid brought into contact with the process gas may be atomized through nozzles to react with the process gas.
Dibasic acid (DBA) is an aliphatic dibasic acid product containing primarily glutaric, succinic and adipic acids available commercially from companies such as INVISTA, a wholly owned subsidiary of Koch Industries, Inc., Wichita, Kans., USA and Sigma-Aldrich Corporation, St. Louis, Mo., USA. DBA is a substance used within wet flue gas desulphurization (WFGD) systems to improve sulphur dioxide removal efficiency. DBA acts as a buffer in WFGD systems to boost the absorption liquid's availability to absorb sulphur dioxide, to thereby remove sulphur dioxide from the process gas, with reduced pH level drop of the absorption liquid. Hence, DBA increases the alkalinity of the absorption liquid without changing the pH of the absorption liquid.
Because DBA use increases the efficiency of sulphur dioxide removal from process gas, DBA use is very desirable. Unfortunately, use of DBA in WFGD systems is relatively expensive. Further, overages or overdosing of DBA in the absorption liquid may lead to waste water treatment difficulties and additional expenses associated therewith. Accordingly, in order to minimize WFGD system operating expenses and avoid waste water treatment difficulties and expenses associated therewith, DBA concentration maintenance to a level sufficient to achieve a desired WFGD system efficiency without overdosing thereof, is desirable.
Consequently, there is a need for continuously measuring DBA concentration in a substance in a gas cleaning device for process gas cleaning treatment process control.